ANAHEIM, CALIF. – More than half of the BP measurements of patients in the SPRINT trial were at least partially attended by clinic staff, but those efforts made no difference in outcomes, according to a survey presented by SPRINT investigators at the American Heart Association scientific sessions.
“It really didn’t matter” whether measurements were observed or not; blood pressure control and outcomes – fewer deaths and cardiovascular events when hypertension was treated to below 120 mm Hg instead of below 140 mm Hg – were largely the same either way, said the survey’s lead investigator Karen C. Johnson, MD, professor of women’s health and preventive medicine at the University of Tennessee in Memphis.
Dr. Karen Johnson
What did matter were the other measures SPRINT [Systolic Blood Pressure Intervention Trial] took to ensure accurate blood pressure measurement, including patients resting for 5 minutes; three automated readings taken afterward then averaged; proper cuff size; feet flat on the floor while patients sat; arms at proper level, and no talking, texting, or filling out forms during the reading, Dr. Johnson said (N Engl J Med. 2015 Nov 26;373[22]:2103-16).
“If you do [those things], then it doesn’t matter if somebody is in the room or not; you can treat to the levels we are talking about,” said William Cushman, MD, professor of medicine and physiology at the university, and also a SPRINT investigator.
Dr. William Cushman
Although the SPRINT researchers hadn’t addressed the issue before the AHA meeting, it’s been widely thought, and even reported in some places, that blood pressures in the trial were unattended. The misperception has led to anxiety about how to apply SPRINT to everyday practice, since few clinics are set up to have patients sit alone for 5 or 10 minutes for a blood pressure.
To address the concern, the SPRINT team surveyed study sites after the trial ended. It turned out that 4,082 subjects were at sites where patients were usually left alone for both the 5-minute rest period and the three BP readings, and 2,247 were at sites where staff usually attended both; 1,746 were at sites that left patients alone for the rest period only; and 570 were at sites where patients were alone only for the BP readings.
Observation had no impact on blood pressure. In the intensive arm, participants achieved and maintained an average systolic BP of about 120 mm Hg in all four groups. In the standard treatment arm, that average was about 135 mm Hg in all four groups. “When we look at the number of medications used, they were very similar in all four blood pressure groups,” with intensive treatment patients taking an average of one extra drug, Dr. Johnson said.
Intensive treatment, versus standard treatment, reduced cardiovascular events to a similar extent in patients who were alone for the entire blood pressure reading (by 38%) and those who were accompanied throughout (by 36%). For reasons that are not clear, intensive treatment did not significantly reduce risk among subjects who were observed during rest or observed for blood pressure readings. Both groups had lower Framingham 10-year cardiovascular disease risk scores, which may have been a confounder.
Meanwhile, the rate of adverse events and total mortality – lower with intensive treatment – did not vary by observation, Dr. Johnson said.
The survey excluded 716 subjects at 14 study sites who could not be classified into one of the four BP observation categories.
SPRINT was sponsored by the National Institutes of Health. Doctors Johnson and Cushman didn’t have any disclosures.